From: Conor Dooley <conor@kernel.org>
To: Sean Nyekjaer <sean@geanix.com>
Cc: Conor Dooley <conor.dooley@microchip.com>,
robh+dt@kernel.org, Lee Jones <lee@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Conor Dooley <conor+dt@kernel.org>,
pascal Paillet <p.paillet@foss.st.com>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/3] dt-bindings: mfd: stpmic1: add fsl,pmic-poweroff property
Date: Wed, 24 May 2023 20:57:16 +0100 [thread overview]
Message-ID: <20230524-cider-unarmored-b1141db1030b@spud> (raw)
In-Reply-To: <24418459-DE19-4575-835B-8673F279993C@geanix.com>
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Hey Sean, Lee,
On Wed, May 24, 2023 at 12:30:59PM +0200, Sean Nyekjaer wrote:
> > On 24 May 2023, at 12.08, Conor Dooley <conor.dooley@microchip.com> wrote:
> > On Wed, May 24, 2023 at 10:16:13AM +0200, Sean Nyekjær wrote:
> >>> On 23 May 2023, at 19.29, Conor Dooley <conor@kernel.org> wrote:
> >>> On Tue, May 23, 2023 at 11:55:50AM +0200, Sean Nyekjær wrote:
> >>>>> On 16 May 2023, at 20.06, Conor Dooley <conor@kernel.org> wrote:
> >>>>> On Tue, May 16, 2023 at 03:22:24PM +0200, Sean Nyekjaer wrote:
> >>>>>> + st,pmic-poweroff:
> >>>>>> + $ref: /schemas/types.yaml#/definitions/flag
> >>>>>> + description: |
> >>>>>> + if present, configure the PMIC to shutdown all power rails when
> >>>>>> + power off sequence have finished.
> >>>>>> + Use this option if the SoC should be powered off by external power management
> >>>>>> + IC (PMIC).
> >>>>>
> >>>>> Just reading this description, this is sounding quite like a "software
> >>>>> behaviour" type of property, which are not permitted, rather than
> >>>>> describing some element of the hardware. Clearly you are trying to solve
> >>>>> an actual problem though, so try re-phrasing the description (and
> >>>>> property name) to focus on what exact hardware configuration it is that
> >>>>> you are trying to special-case.
> >>>>> Krzysztof suggested that the samsung,s2mps11-acokb-ground property in
> >>>>> samsung,s2mps11.yaml is addressing a similar problem, so that could be
> >>>>> good to look at.
> >>> The description for the property that Krzysztof mentioned is
> >>> samsung,s2mps11-acokb-ground:
> >>> description: |
> >>> Indicates that ACOKB pin of S2MPS11 PMIC is connected to the ground so
> >>> the PMIC must manually set PWRHOLD bit in CTRL1 register to turn off the
> >>> power. Usually the ACOKB is pulled up to VBATT so when PWRHOLD pin goes
> >>> low, the rising ACOKB will trigger power off.
> >>>
> >>> In other words, I am asking what (abnormal?) scenario there is that means
> >>> you need the property, rather than what setting the property does.
> >>> Or am I totally off, and this is the only way this PMIC works?
> >>
> >> Indicates that the power management IC (PMIC) turn-off condition is met
> >> by setting the SWOFF bit in the main control register (MAIN_CR) register.
> >> Turn-off condition can still be reached by the PONKEY input.
> >>
> >> ?
> >>
> >> I must admit I’m somewhat lost here :)
> >
> > Sorry about that. I'm trying to understand what is different about your
> > hardware that it needs the property rather than what adding the property
> > does. If you look at the samsung one, it describes both the
> > configuration of the hardware ("ACOKB pin of S2MPS11 PMIC is connected to
> > the ground") and how that is different from normal ("Usually the ACOKB is
> > pulled up to VBATT so when PWRHOLD pin goes low, the rising ACOKB will
> > trigger power off.")
> >
> > Looking at your datasheet, you don't have such a pin though - just the
> > sw poweroff bit & the PONKEY stuff. My angle is just that I am trying
> > to figure out why you need this property when it has not been needed
> > before. Or why you would not always want to "shutdown all power rails
> > when power-off sequence have finished". I'm sorry if these are silly
> > questions.
> >
>
> No silly questions, maybe they trick me to come up with the correct answer :D
>
> Basically without this, you won’t be able to power off the system
> other than hitting the PONKEY.
> So it’s a new feature that wasn’t supported before.
> Maybe this feature should not be optional?
Yeah, I suppose that is the rabbit-hole that the silly questions lead
down. I don't know the answer to that though. Maybe Lee does?
> If st,pmic-poweroff == true:
> System will power off as the last step in the power off sequence.
> If st,pmic-powerof == false:
> System will reboot in the last step in the power off sequence.
>
> I thought of this, as an always on system failsafe.
>
> /Sean
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next prev parent reply other threads:[~2023-05-24 19:57 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-16 13:22 [PATCH v2 1/3] mfd: stpmic1: fixup main control register and bits naming Sean Nyekjaer
2023-05-16 13:22 ` [PATCH v2 2/3] mfd: stpmic1: add pmic poweroff via sys-off handler Sean Nyekjaer
2023-05-25 11:46 ` Lee Jones
2023-05-16 13:22 ` [PATCH v2 3/3] dt-bindings: mfd: stpmic1: add fsl,pmic-poweroff property Sean Nyekjaer
2023-05-16 18:06 ` Conor Dooley
2023-05-23 9:55 ` Sean Nyekjær
2023-05-23 17:29 ` Conor Dooley
2023-05-24 8:16 ` Sean Nyekjær
2023-05-24 10:08 ` Conor Dooley
2023-05-24 10:30 ` Sean Nyekjaer
2023-05-24 19:57 ` Conor Dooley [this message]
2023-06-01 7:12 ` Krzysztof Kozlowski
2023-06-01 14:05 ` Sean Nyekjaer
2023-06-01 15:25 ` Krzysztof Kozlowski
2023-06-01 20:03 ` Conor Dooley
2023-05-25 11:46 ` [PATCH v2 1/3] mfd: stpmic1: fixup main control register and bits naming Lee Jones
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